Import Error - deadlock detected while trying to lock object TEST.CLIENT

Have received the below error while doing schema level refresh.

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Processing object type SCHEMA_EXPORT/VIEW/GRANT/OWNER_GRANT/OBJECT_GRANT
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT

ORA-39083: Object type REF_CONSTRAINT failed to create with error:
ORA-04020: deadlock detected while trying to lock object TEST.CLIENT
Failing sql is:
ALTER TABLE "TEST"."TRANSACTION" ADD CONSTRAINT "TRANSACTION_FK" FOREIGN KEY ("LAST_UPDATED_BY_CLIENT_ID") REFERENCES "TEST"."CLIENT" ("CLIENT_ID") ENABLE;

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First check for locked objects in the database. using the below queries.

SQL> sqlplus / as sysdba

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SQL> select * from v$locked_object;

no rows selected

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SQL> column blocker format a25
SQL> column blockee format a25
SQL> column sid_serial format a10
SQL>
SQL> select
  2  (select username || ' - ' || osuser from v$session where sid=a.sid) blocker,
  3  a.sid || ', ' ||
  4  (select serial# from v$session where sid=a.sid) sid_serial,
  5  ' is blocking ',
  6  (select username || ' - ' || osuser from v$session where sid=b.sid) blockee,
  7  b.sid || ', ' ||
  8  (select serial# from v$session where sid=b.sid) sid_serial
  9  from v$lock a, v$lock b
 10  where a.block = 1
 11  and b.request > 0
 12  and a.id1 = b.id1
 13  and a.id2 = b.id2;

no rows selected

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Then try to execute the failed Query connecting to the schema. like below

Connect to that schema & execute.

SQL> ALTER TABLE "TEST"."TRANSACTION" ADD CONSTRAINT "TRANSACTION_FK" FOREIGN KEY ("LAST_UPDATED_BY_CLIENT_ID") REFERENCES "TEST"."CLIENT" ("CLIENT_ID") ENABLE;

Table altered.